tree e8353e3d029892938a7795720a8ccbb123f0b851
parent f5cdaccdf71267cf578010b46036dbd1b93d6e13
author cdumez@apple.com <cdumez@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1575590172 +0000
committer cdumez@apple.com <cdumez@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1575590172 +0000

Optimize IPC::Connection::SyncMessageState methods
https://bugs.webkit.org/show_bug.cgi?id=204890

Reviewed by Alex Christensen.

Optimize IPC::Connection::SyncMessageState methods. We are seeing lock contention on some (app launch)
benchmarks, resulting in the main thread yielding for 10ms.

* Platform/IPC/Connection.cpp:
(IPC::Connection::SyncMessageState): Make constructor private since this is a singleton class.
(IPC::Connection::ConnectionAndIncomingMessage): Add convenience dispatch() method.

(IPC::Connection::SyncMessageState::processIncomingMessage):
Drop the lock as early as possible, *before* calling RunLoop::main().dispatch().

(IPC::Connection::SyncMessageState::dispatchMessages):
Drop allowedConnection parameter and simplify the code a lot as a result. Only dispatchMessagesAndResetDidScheduleDispatchMessagesForConnection()
needed the pass an allowedConnection but having dispatchMessagesAndResetDidScheduleDispatchMessagesForConnection() call dispatchMessages() was
inefficient since it would cause us to grab the lock in dispatchMessagesAndResetDidScheduleDispatchMessagesForConnection() to update
m_didScheduleDispatchMessagesWorkSet, then release it, then grab the lock again in dispatchMessages() for m_messagesToDispatchWhileWaitingForSyncReply.

(IPC::Connection::SyncMessageState::dispatchMessagesAndResetDidScheduleDispatchMessagesForConnection):
Grab the lock only once to update m_didScheduleDispatchMessagesWorkSet and m_messagesToDispatchWhileWaitingForSyncReply, instead of doing it in 2
separate steps, each one taking the lock.

(IPC::Connection::waitForMessage):
(IPC::Connection::waitForSyncReply):
(IPC::Connection::dispatchSyncMessage):
stop passing a null allowedConnection when calling dispatchMessages().

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@253183 268f45cc-cd09-0410-ab3c-d52691b4dbfc